How can I search for keywords across multiple tables in PHP and MySQL?

PHP MySQL Keyword Search Across Multiple Tables

Encountering limitations when querying multiple tables for a keyword, this question explores how to expand database searches efficiently. Starting with a query that searches a single table, the user seeks to modify it to scan various fields within multiple related tables.

The provided solution utilizes the UNION operator to combine three separate queries into one comprehensive one. Each individual query targets a specific table and its columns for content and title matching. By combining these queries with UNION, the resulting query searches across multiple tables concurrently, examining both content and title fields for the specified keyword.

To differentiate the results across tables, an additional column is added to each subquery, labeling each entry as "msg" (messages), "topic" (topics), or "comment" (comments). This column enables clear identification of the table of origin for each search result.

Thus, the final query allows for comprehensive keyword searches spanning multiple tables, with the ability to pinpoint the source of each returned result. This approach ensures efficient data retrieval while maintaining a structured and informative output.

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